1. Field of the Invention
This invention relates to an image forming apparatus which forms an image on a transfer material by an electrophotographic process.
2. Description of the Related Art
In a fuser incorporated in an image forming apparatus using an electrophotographic process, a thin heating roller is used as a heat roller fixing system.
In addition, control is used which lowers the heating preset temperature because the heating roller and pressure roller get warm sufficiently as a result of consecutive copying.
However, after the copying has been completed or the sheets of paper have passed, the heating roller and pressure roller are warmed sufficiently by remaining heat or the like. Thereafter, when the temperature of heating roller is returned to the heating present temperature before the temperature drop, an overshoot phenomenon takes place, which is a problem.
When a heating roller containing a thin electrically conductive sheet is used for induction heating, temperature changes are particularly large. In addition, when a heater lamp is used, the response is poor, which causes the following problems: damage to parts and the corruption of such images as high-temperature offset images in subsequent copying.